The Food and Drug Administration says it is time for cosmetic companies to stop talking and start changing labels that claim skin creams can retard or reverse aging of the skin.

The federal agency wrote 22 companies on Monday that it will take another look at the labels in 30 days and then crack down on any that persist in misleading claims."We believe that FDA has clearly stated its views regarding the types of claims that can appropriately be made on cosmetic skin care products and the types of claims that make skin products unapproved new drugs," wrote John M. Taylor, associate commissioner for regulatory affairs.

"Accordingly, we do not believe that a detailed review or a prolonged discussion regarding individual product labeling is necessary. We hope that you will make the changes in your labeling that are necessary to bring it into compliance with the act and with FDA's stated views."

The Food, Drug and Cosmetic Act defines cosmetics, which can be sold without pre-approval by the FDA, as products intended to cleanse or to beautify superficially.

In warnings to the cosmetic industry last year, the agency said when a product is said to counteract, retard or control the aging process or to rejuvenate, repair or renew the skin, then those statements put the product in the drug category with all its stringent scientific review requirements. Such claims indicate that a "function of the body, or that the structure of the body, will be affected by the product."

The FDA said then it was "unaware of any substantial scientific evidence that demonstrates the safety and effectiveness" of the so-called anti-aging skin products.